At level 16, your skill selection is going to be pretty narrow.

Your most powerful solo skill in your arsenal is Strife at this point. The morph to funnel health is better in a group, but swallow soul is better for solo. The idea being that you heal while you damage and you out heal the enemies damage. You could honestly clear the entire main quest with just this skill (not saying you actually should). This is perhaps the best low level skill on this game.

Nightblades do have a great CC in Mass Hysteria, but it's really not all the useful in PVE just questing. It will also be a little while before you get it as well.

You could also look to destructive touch (third destro skill) combined with a fire staff. It is not bad as its a knockback so you can create a little distance from a melee add if needed. In PVE, you wont have room on your bars for it at endgame.

2 other class skills that you want to make a priority to unlock are path of darkness (ground AOE DOT and heal if you morph to refreshing path), and crippling grasp (morph of cripple). Its a strong single target dot, but also gives you major expedition so you are really fast and can kite as needed.

You also want to get elemental blockade (morph of wall of elements in destro staff). Its basically a ground AOE that does a lot of damage.

If you come up to a group of 3 mobs, cast path, blockade, cripple (on tankiest target), and then spam strife until things die. You really shouldnt need a hard CC for most overland/quest content.

Lastly, make sure you are wearing 5 pieces of light armor so you can unlock and use the light armor skill (must be wearing 5 pieces of light to use the skill). It is a big shield, that you want to get in the habit of using. Nightblades survive in this game with high heals, movement, and a shield in those oh crap moments.